The present invention relates to circular knitting machines for manufacturing hosiery articles, and in particular to a system and a method for manufacturing hosiery articles that removes wrinkles in the hosiery cuff.
Conventional circular knitting machines are electronically programmable to control the relative movements of a knitting cylinder, needles, dial jacks, sinkers, stitch cams, thread guides, and other components and elements of the machine in order to operate the knitting process and to obtain different kinds of knitting patterns. Needles, sinkers, and jacks are arranged at equal distances around the circumference of a knitting cylinder. The cylinder moves vertically. A dial jack is a steel blade that moves horizontally across the cylinder and controls the movement of knitting needles. A dial is a circular plate with radially positioned slots to hold a set of knitting needles. A dial is connected to a dial head and is aligned over the top of a knitting cylinder. When a dial jack moves across a knitting cylinder, it holds a course of thread in place. Dial jacks are connected to a dial such that when a dial moves up or down, the dial jacks move correspondingly. If a dial jack is holding a course of thread in an article being knitted and the dial is moved, the article being knitted moves in correspondence with the movement of the dial.
Tubular hosiery articles, for example socks, are typically knit on circular knitting machines. When knitting is complete and socks come off a knitting machine, the cuff, or welt, is generally wrinkled, or xe2x80x9cbunched.xe2x80x9d For socks with larger cuffs, such as quarter socks, wrinkling is a particular problem. After knitting is complete, the tubular hosiery blanks are transported away from the knitting machine, for example to another machine where the toe portion is closed by sewing a toe seam. Because toe seams are often sewn on the inside of a sock, socks are turned inside out to position them for sewing an internal seam.
In conventional manufacturing processes, socks are transported directly from a knitting machine to a sewing machine or station for toe closure. At the sewing station, socks can be manually turned inside out and the xe2x80x9cbunchedxe2x80x9d cuff straightened by hand in the process. In other processes, socks are transported from a knitting machine to a sewing station by a pneumatic means. For example, in typical knitting of tubular hosiery blanks, a hosiery takedown device applies suction to a hosiery blank while the blank is being knit. When the knitting is finished, a vacuum is applied and pulls the blank away from the knitting elements and transports it to another location. In such a pneumatic transportation system, the socks can be turned inside out, or reversed, through pneumatic tensioning in the annular space between an outer tube and an inner tube. Pneumatic tensioning and reversing processes can provide incidental straightening of a small portion of wrinkles in a cuff. However, the majority of wrinkles remain in a sock having a thick cuff, such as a quarter sock, even after application of pneumatic tension in conventional knitting machines.
These conventional approaches to de-wrinkling cuffs in socks have disadvantages and are particularly unsuitable in some manufacturing processes. A disadvantage of conventional pneumatic tensioning devices and processes is that additional machinery and complex operations are involved. In addition, certain intervening steps in newer manufacturing practices and procedures cause de-wrinkling at the toe sewing stage to be ineffective. In particular, knitted socks are often shipped to a remote location for finishing. In such a situation, socks may be transported directly from a knitting machine to a bleaching vat and then dried at high temperatures in an industrial drier. With no de-wrinkling procedure prior to bleaching and drying, cuff wrinkles are heat-set by the high drying temperatures.
Another step that compounds wrinkle-setting problems involves packaging socks for transportation to a remote location for finishing operations. To conserve shipping space and costs, socks transported to a finishing plant for processing steps such as sewing are often highly compacted into a container or bail using a hydraulic press. Textile materials that have undergone such high-pressure compaction can be uncompacted with techniques such as washing. However, unstraightened cuff wrinkles that are subsequently highly compacted can become permanently set. Various textile fibers that are wrinkled and then compacted can be damaged beyond usability.
Socks that have a cuff, or turned welt, that is full-length are more susceptible to damage from wrinkles that are heat-set and/or compacted due to a larger amount of material in the cuffs. For example, xe2x80x9cquarter socksxe2x80x9d having a full-length cuff exhibit an unacceptably high rate of damage due to wrinkles set by heat-drying and compaction processes. A quarter sock typically has double the number of courses in the top cuff portion as a crew sock, for example. While a typical crew sock may have 30 courses of thread, a quarter sock may have 60 courses. The mass of such a double-thickness cuff causes the cuff to bunch and not feed down the knitting cylinder dial without intervention. Bunching of a sock cuff inside the knitting cylinder creates wrinkles in the cuff.
Thus, there is a need to provide a system and method for automatically removing the majority of wrinkles in hosiery, particularly in hosiery having large cuffs, during manufacturing on a circular knitting machine. There is also a need for a system and method for automatically removing the majority of wrinkles in hosiery cuffs that facilitates removal of the hosiery article from a circular knitting machine. There is also a need for a system and method for automatically removing the majority of wrinkles in hosiery in a circular knitting machine that is simple to construct and operate.
The present invention provides a programmable system and method for dewrinkling, or removing wrinkles from, a hosiery article in a circular knitting machine. An embodiment of the present invention comprises a dial head movable between a down position and an up position, a means for moving the dial head downward and upward, and a dial head locking mechanism for locking and unlocking the dial head. When the dial head is unlocked and moved to the up position, wrinkles are removed from the hosiery article. Such embodiments can include a means for applying suction to the hosiery article. In embodiments, the means for moving the dial head downward and upward comprises a vertical air piston. In other embodiments, the dial head locking mechanism comprises a horizontal air piston.
A system and method of the present invention include a means for moving the dial head downward and upward and a dial head locking mechanism that are each programmable for automatic actuation at predetermined times during a knitting cycle. In embodiments, the means for moving the dial head downward and upward is programmed to move the dial head to the up position immediately after the top course of the cuff is knit.
In the present invention, the dial head is moved up a predetermined distance from the dial head down position. In embodiments, the predetermined distance the dial head is moved up from the dial head down position comprises the range of one-fourth inch to one inch. In preferred embodiments, the predetermined distance the dial head is moved up from the dial head down position is three-fourths inch.
A dewrinkling system and method of the present invention provides for removal of wrinkles from an entire hosiery article. Embodiments of the present invention are particularly well-suited for removing wrinkles from hosiery articles having thick cuffs, such as quarter socks with double-thickness cuffs.
In embodiments of the present invention, each air piston is connected to a source of compressed air by a separate air tube, an electrovalve for each air piston is connected to the source of compressed air, and each electrovalve is programmable to turn on and off a flow of compressed air to the respective air piston at predetermined times during a knitting cycle. Embodiments can include an air flow adjustment valve connected to each air tube for buffering the flow of compressed into the air piston connected to the air tube.
An embodiment of a method for dewrinkling a hosiery article in a circular knitting machine comprises unlocking the dial head and moving the dial head to the up position to stretch the hosiery article, wherein wrinkles are removed from the hosiery article. Such a method can include applying suction to the hosiery article.
Embodiments of a method comprise programming a circular knitting machine to knit a predetermined number of courses of a hosiery article by rotating the dial a corresponding number of revolutions of the knitting cylinder at particular times during the knitting process. For example, a knitting machine can be programmed to knit a predetermined number of courses of a hosiery article before and after disengaging the dial shaft latch from the dial shaft, after moving the dial head to the up position, and after moving the dial head to the down position. Such a predetermined number of cylinder revolutions allows time for the physical operations of the electrovalves, air pistons, and movement of the dial shaft latch and dial head to occur before proceeding to the next step in the dewrinkling process.
Features of a hosiery dewrinkling system and method of the present invention may be accomplished singularly, or in combination, in one or more of the embodiments of the present invention. As will be appreciated by those of ordinary skill in the art, the present invention has wide utility in a number of applications as illustrated by the variety of features and advantages discussed below.
A hosiery dewrinkling system and method of the present invention provides numerous advantages over prior approaches to removing wrinkles in hosiery articles. For example, the present invention advantageously provides a system and method for dewrinkling hosiery that is efficient and effective. The present invention can be incorporated into a conventional knitting machine, providing the benefit of removing wrinkles in a hosiery article without transporting the articles to another work station. Another advantage is the present invention can be programmed into a knitting machine to remove wrinkles from hosiery articles automatically. As such, the present invention provides a system and method for dewrinkling hosiery articles that is integrated into normal knitting processes without slowing production time. By avoiding manual straightening of wrinkles in hosiery cuffs, production times can be enhanced.
Another advantage is that the present invention provides a system and method for dewrinkling hosiery articles that eliminates virtually all of the wrinkles in a sock, including socks having a thick cuff or welt.
Another advantage is that the present invention provides a system and method for removing wrinkles during the knitting process, prior to drying articles, and heat-setting wrinkles therein, and before articles are compacted.
Another advantage is that by removing wrinkles during the knitting process, the present invention facilitates removal of a thick-cuffed hosiery article from a knitting cylinder.
Still another advantage is that the present invention provides a dewrinkling device and system that has a simple construction and is uncomplicated in operation and servicing. A system and method for dewrinkling hosiery articles of the present invention can advantageously be used on different types of knitting machines.
Yet another advantage is that the present invention is reliable in operation due to a smooth moving design including air flow adjustment valves, a horizontal air piston spring, and electronic control of air flow. These features decrease the wear and tear of the dewrinkling system components and prolong the service life of the system and the knitting machines used thereon.